The second type of architectures includes the schemes developed for the cat-basis encoding [1]}, [2]}, the GKP encoding [3]}, [4]}, and the dual-rail encoding [5]}.
These approaches must contend with the non-deterministic generation of individual qubit states, particularly in the former two cases where the states have a complicated structure.
The latter case has the added challenge of non-deterministic entangling or “fusion” gates, which are required to grow a cluster state.
Each gate is eventually implemented by consuming probabilistically generated photons, which imposes formidable multiplexing requirements for cluster state generation—unlike schemes for generating CV cluster states.
